Process of degasifying coal and other carbonaceous material in situ



July 19, 19 2. L, R NNB} mamas PROCESS OF DEGASIFYING 'COAL AND OTHERCARBONACEOUS MATERIAL IN SITU I I legglo, 15m '2 Sheets-Sheet 1 I Y fl'6 18 J H 2] Ywm v A 1 g 5 9 I0 LEO RANNEY iNVENTOR ATTORNEYS julylg,1932. RANNEY Q 1,861,758

PROCESS OFDEGASIFYING COAL AND OTHER CARBONACEOUS MATERIAL IN SITU FiledJuly 10, 1931 2 She'ets-Sheet 2 LEO RANNEY INVENTOR BY/JKWWM ATTORN EYSPatented July 19, 1932 UNITED STATES LEO RANNEY, on NEW YORK, my.

PROCESS OF DEGASIFYING COAL AND OTHER CARBONACEOUS MATERIAL IN SI'I'U 1Application filed July 10, 1931. Serial No. 550,009.

This invention relates to improvements in the process of degasifyin'gcoal and other carbonaceous materials in situ.

The primary object of this invention 1s to 5 provide a method for theremoval of gas from an area in a coal seam or 'other porous bed prior tothe extending of mining operations to that area. 7

A further object of the invention is .to re- 10 move one of the everpresent hazards to coal mining, that is, the collection of combustiblegases in the workings, and to make available for use what is now a wasteproduct in the industry.

A still furtherobject of the invention is to provide a method forpreventing the flow of gas from unworked areas, or from gas bearingstrata adjacent thereto, into the workings of coal mines and thereby toreduce the cost of mine ventilation.

Heretofore, it has been proposed to remove mineral oil and, gases frombituminous and gaseous deposits with the aid of movable air dams and bythe drilling of bore holes into that part of the oil bearing depositblocked off by the movable air dam. Such a method may be applicable tothe removal of oil and gas from loosely consolidated deposits, such asoil sands and gravel, but is entirely impracticable in connection withthe degasification of solid or highly consolidated gas hearing deposits,such as coal seams and shale, princially due to the fact that it doesnot provide adequate means to prevent the infiltration of air, nor doesit expose sufiicient surface areas for the exudation of the gas.

Gas reposing in an earth formation must lie within the pores betweengrains, if in a sand or gravel bed, but within coal seams by far themajor percentage of gas to be found is occluded or absorbed within thecoal itself and only a small part of the gas occupies the minutefissures, cleavage and bedding planes extending longitudinally andhorizontally in the coal seam. This occluded or absorbed gas is drivenoff gradually during mining operations, so that it is a continuinghazard to workmen and a handicap to mine ventilation, and the loss of itis a waste of a natural resource. It is not unusual to encounter Myprocess comprises the remova 0 from any area in a coal seam or otherporous 56 o bed previous to the commencement of mining operations inthat area or in the removal of gas coincidental with vthe extending ofthe workings of the mine.

With the foregoing objects outlined and 60 with other objects in view,which will appear as the description proceeds, the invention consists ofthe novel features hereinafter described in' detail, illustrated in theaccompanying drawings and more particularly $5 pointed out in theappended claims.

In the drawings: I

Figure 1 is a plan view of a degasification system located adjacent tothe old workings of a coal mine. '7

Figure 2 is a vertical section throu h one of the'sapping drifts of thedegasi cation system taken on the line l' 1 of Figure 1.

Figure 3 illustrates means for temporarily sealing the sapping driftsduring the construction of the degasification system.

Figure 4c is a vertical section showing a modified form of the inventionas applied to the removal ofgas from an. area of a coal seam lying belowthe economic limit of coal mining operations.

Figure 5 is a vertical section showing a modified form of the inventionas applied to the removal of gas from the rock adjacent to a coal seam.

Referring to the drawings, 1 represents a shaft --le"ading to theworkings 2 of a coal mine. From the workings 2, I drive a, tunnel 3 intoor adjacent to the coal seam comprising the area to be degasified.leaving sufficient coal or rock pillars 4 for the support of the roof.This tunnel, during the course of construction, may if necessary beventilated by any usual means, such as a brattice and blower, notillustrated.

Having constructed the tunnel 3 of any desired length, I then extendfrom the tunnel 3 into the coal area to be degasified, sappingtunnels 5which may be from 250 to 2000 ft. or more in length, depending upon thearea to be degasilied and which may be of a size capable of use ashaulage ways when mining operations are to be commenced afterdegasification. The first sapping tunnel of the system should be locateda sufficient distance from the old workings to prevent the infiltrationof air therefrom into the degasification system.

In particularly gaseous areas, it may be found advantageous totemporarily seal the sapping drifts 5 at their entrance into the tunnel3, to prevent loss of gas and to simplify the ventilation of the tunnel3.

Referring now to Figure 2, it may be found desirable in certaininstances to increase the exposed surface of the coal to be degasifiedby making borings 9 from the sapping tunnels 5 into the coal seam and insome instances, particularly where subsequent mining of the coal is notintended, to place explosive charges in the bore holes at 10 and toshoot them for the purpose of breaking up the coal scam and exposinglarger surfaces. Ordinarily, it is better practice to shoot theexplosive charges after completion of the degasification system, butprior to completely sealing same.

Having completed the tunnel 3, sapping tunnels 5 and such borings 9 asmay be desirable, I 4 then construct, preferably of concrete pouredunder pressure, one or more barriers 6, 6' and 6", in the open end ofthe tunnel 3 nearest the old workings of the mine or the shaft as thecase may be. A pipe 7 is extended either from the shaft or from the oldworkings through the barriers 6,6 and 6" into the tunnel 3 and isconnected through a suitable pipe 8 to ex-.

hausting pumps and gas reservoirs, not illustrated, located on thesurface of the ground.

I have found that the installation of the barriers, 6, 6 and 6" ofconcrete or other substantially impervious material is not alwayssufficient to prevent the infiltration ofair around the barriers when apartial vacuum is placed on the degasification system. In cases wherethe coal seam consists of a relatively non-porous mass, the infiltrationof air around the barriers 6, 6 and 6 may be prevented by coating thesurface of the coal in the tunnel 3 between the barriers with guniteand/or asphalt paint, also by extending the gunite or asphalt paintcoating along the surface of the coal at the end of the tunnel 3communicating with the shaft or old workings of the mine, and in somecases along the face of coal inthe old workings nearest to the sappingor degasification system.

However, in some instances, it will be found that a coating of guniteor' asphalt paint will not be sufficient to prevent the infiltration ofair. In such instances, L propose to fill the tunnel 3 between thebarriers 6 and 6, and 6 and 6" with a mixture of mud and crude oil orsome other plastic material and in some cases to maintain it underpressure. Upon placing the degasification s stem under partial vacuum,the mud or ot er plastic material will flow into the seams and crevicesof the coal face adjacent to the walls of the tunnel 3 and effectuallyseal the degasification system against the infiltration of air.

Having completed the degasification system and sealed the tunnel 3against the infiltration of air, the degasification system, provided thegas pressure is not sufficient to deliver the gas to storage reservoirs,is placed under partial vacuum and the gas exhausted through the pipe 7and delivered to the surface through pipe 8. It may be found necessaryto discard some of the first gas withdrawn from the degasificationsystem, as itmay be diluted with air and of small commercial value. Assoon as the air content of the gas becomes sufiiciently low, the gasexhausted from the workings may be conducted to any suitable reservoirfor future use.

Referring now to Figure 3, I illustrate means for temporarily sealingthe lateral sapping tunnels 5 during the construction of thedegasification system. A- fiexible curtain 11 of rubberized or othermaterial substantially impervious to gas, which is attached on all foursides to adjustable plates 12 which coopcrate with the rubber gaskets13, is placed in the end of the drift 5 communicating with the tunnel 3,and the plates 12 and the rubber gaskets 13 are compressed against thewalls, roof and floor of the tunnel 5 by any suitable means, to effect atemporary seal substantially impervious to the flow of gas and air. Inthe floor of the tunnel 5, I embed a short pipe 14 with anupwardlyextending elbow. The other end of the pipe 14: passes out beyondthe temporary seal in the sapping tunnels 5 into tunnel 3 and isconnected to the main gas line 7, which is connected by the pipe 8 to asuitable exhauster on the surface of the ground.

The curtain 11 is purposely made slack and is attached at its center tolever 15 which operates the damper or butterfly valve 16 located in pipe14.

en the gas pressure in the sapping drift 5 balances the air pressure inthe tunnel 3, the curtain 11 hangs slack, but as the gas pressure in thesapping drift increases, the curtain is caused to bulge outwardtowar'dthe main tunnel and to open the butterfly valve or damper 16 in pipe 14,thus permitting the application of a vacuum for the removal of theexcess gas from tunnel 5. When the gas pressure in the lateral 5 isagain equalized with the air pressure in tunnel 3, the valve isautomatically closed 0- partially closed by the inward movement .of thecurtain 11. In the event the vacuum becomes too high, the curtain 11will be drawn inward, and will close the valve 16 and permit thepressure to again be equalized. This temporary sealing means is removedupon the completion of the degasification system and prior to sealing oftunnel 3.

Figure 4 illustrates a modification of the process particularl adaptableto steeply dipping carbonaceouslheds but which may e applied to any coalseam having rock adjacent thereto. 17 is a coal seam and 18 the lowestlevel of the coal mining workings therein. l9is a shaft driven in therock adjacent to the coal seam to a point considerably lower than thelowest workings and leading to the sapping tunnels 20 extendingsubstantially at right angles to the shaft and substantially parallel tothe .strike of the coal seam. 21

and 21 are sapping tunnels and bore holes,

drilled from the tunnels 20 through the intervening rock and to andthrough the coal seam itself. These sapping tunnels or bore holes may bespaced at intervals of 20, 40 or 60'feet or more, depending uponconditions encountered.

During construction the sapping tunnels 21 may if desired be temporarilysealed as previously described. Holes 21' may, if desired, be loadedwith explosives and the mouth of the hole leading into the sappingtunnel sealed to prevent the escape of gas thereinto during developmentwork.

Electric wiring, not illustrated, is extended through the barrier 24 andto the surface of the ground to enable the charges to be exploded one ata time after the degasification system has been installed. Theshootingof the holes blows out the seals and establishes open communication withthe sapping tunnels and at the same time fractures the coal about theholes and thereby exposes a large area for the exudation of gastherefrom into the sapping tunnels.

In cases where a water table 22 exists within the coal seam at adistance below the level of these sapping tunnels, if the water tablehas a tendency to rise as gas is removed from the coal seam above it,advantage is taken of this fact and the water is utilized to lift thegas through the coal seam toward the row of tunnels 21 and bore holes 21through which gas is produced.

Degasification pipe 23 is extended downward in the shaft to drawgas-from thedegasification system. A barrier 24or heavy bulkhead ofconcrete surrounds the pipe. Through this seal is a manhole, notillustrated, through which the gases of explosion from the firing ofcharges in the holes 21 are allowed to escape. When all these chargeshave been fired, preferably one at a time, the manhole is closed and aseal of mud or other plastic or impermeable substance is placed in theshaft directly above the concrete bulkhead 24 to prevent theinfiltration of air into the degasification system. Suction is thenapplied to the above ground end of pipe 23, and a partial vacuum createdin the tunnels 20 and 21 and holes 21, the gas from the coal seam beingdelive'red through pipe 22 to suitable reservoirs. In some instances, itwill be found that gas is not only occluded in the coal seam, but in theroof rock and floor rock above and below' the seams. In such cases, itwill be necessary to provide means not only for the removal of theoccluded gas from the coal seam but for the removal of the interstitialgas from the roofand floor rock.

Referring now to Figure 5, 5 is a sapping tunnel in the coal seamsimilar to those illustrated in'Figure 1. From the sapping tunnel, Idrill bore holes 25 beyond the coal seam into the roof and floor rockadjacent thereto,

and if the floor and roof rock 26 are not sufsired to degasify may beremoved in advance of the commencement of mining operations and saved,and at the same time prevented from filtering into the workings.

From the above description taken in connection with the drawings, it isbelieved that those skilled in the art will clearly understand thepresent invention, and it is manifest that changes may be made in thedetails disclosed without departing from the spirit of the invention asexpressed in the claims.

What I claim and desire to secure by Letters Patent is:

1. The process of extracting methane gas from coal deposits in situwhich process consists in constructinga tunnel system consisting of oneor more tunnels in the area of the coal deposit to be degasified,sealing said area against the infiltration of atmospheric air, placingthe sealed area under partial vacuum and removing the occluded gas fromthe coal deposit. a

2. The process of extracting methane gas from coal deposits in situwhich process consists in constructing a tunnel system consisting of oneor more tunnels into the area of the coal deposit to be degasified,drilling bore holes from the said tunnels into the coal deosit, placingexplosive charges in the bore oles and exploding same to expose largesurfaces of the coal, sealing said area against the infiltration ofatmospheric air, placing the sealed area under partial vacuum andremoving the occluded gas from the coal deposit.

3. The process of extracting methane gas from coal deposits in situ,which process consists in constructing one or more tunnels in the rockadjacent to the coal seam to be degasified. driving spaced tunnels fromthe tunin the rock and s aced tunnels in the coal seam a ainst the infitration of atmospheric air, p acing the degasification system underpartial vacuum and removing the occluded gas from the coal seam.

4. The process of extractin methane gas from coal deposits in situ whicprocess comprises constructing a tunnel system consisting of a tunnelandconnecting sapping tunnels into the coal deposit to be degasified,

sealing the open end of the tunnel system against the infiltration ofatmospheric air, placing the sealed tunnel system under partial vacuumand removing the occluded gas from the coal deposit.

5. The process of extracting methane gas from coal deposits in situwhich process consists in constructing a tunnel system consisting of oneor more tunnels into the area of the coal deposit to be degasified,constructing two or more spaced barriers in the open end of the tunnelsystem, filling the space between the barriers with a plastic materialsubstantially impervious to the flow of air and gas,

placing the sealed tunnel system under partial vacuum to cause theplastic material to flow into the crevices and pores of the coal faceadjacent to the barriers to prevent the infiltration of atmospheric airand removing the occluded gas from the coal deposit.

6. The process of sealing a tunnel system in a coal deposit against theinfiltration of atmospheric air, which process consists in constructingin the open end of the tunnel system, two or more spaced barriers, andfilling the space between the barriers with a plastic materialsubstantially impervious to the flow of air and gas.

7. The process of sealing a tunnel system in a coal deposit against theinfiltration of atmospheric air. which process consists in constructingin the open end of the tunnel system, two or more spaced barriers, andfilling the space between the barriers with a plastic materialsubstantially impervious to the flow of air and gas and maintaining theplastic material under pressure.

8. The process of sealing a tunnel system in a coal deposit against theinfiltration of atmospheric air. which process consists in constructingin the open end of the tunnel system two or more spaced barriers andfilling the space between the barriers with a plastic materialsubstantially impervious to the flow of gas and air and placing thetunnel system under partial vacuum to cause the plastic material to flowinto and fill the crevices of the coal face adjacent to the barrier.

9. The process of constructing a degasification system in a gas bearingcoal seam,

' which process consists in constructing a tuncape of gas, removing thetemporary seals of the spaced tunnels and sealing the degasificationsystem against the infiltration of atmospheric air.

10. The process of constructing a degasification system in a gas bearingcoal seam, which process consists in constructing a tunnel into the coalseam, constructing communicating spaced tunnels from said tunnel intoother parts of the coal seam, temporarily sealing the spaced tunnels toprevent the escape of gas, automatically equalizing the pressure of gasin the spaced tunnels with the pressure of atmospheric air in the maintunnel, removing the temporary seals of the spaced tunnels and sealingthe degasification system against the infiltration of atmospheric air.

11. The process of extracting methane gas from coal deposits in situ,which process consists in constructing sapping tunnels below the coalseam to be degasified, drilling spaced bore holes from the sappingtunnels into and through the coal seam, sealing the sapping tunnels andbore holes against the infiltration of atmospheric air, placing thedegasification system consisting of the sapping tunnels and bore holesunder partial vacuum and removing the occluded gas from the coal seam.

12. The process of extracting methane gas from coal deposits in situ,which process consists in constructing sapping tunnels below the coalseam to be degasified, drilling spaced bore holes from the sappingtunnels into and through the coal seam, placing explosive charges in thebore holes, temporarily sealing the bore holes to prevent the escape ofgas into the sapping tunnels, exploding the explosive charges tofracture the coal seam and break the temporary seals, sealing thedegasification system comprising the sapping tunnels and bore holesagainst the infiltration of atmospheric air, placing the degasificationsystem under partial vacuum and removing the occluded gas from the coalseam.

13. The process of extracting methane gas from gas bearing rock adjacentto a coal seam, which process comprises constructing a tunnel into thecoal seam, drilling bore holes from the tunnel into and through the coalseam and into the gas bearing rock, sealing the open end of the tunnelagainst the infiltration of atmospheric air, placing the degasificationsystem comprising the tunnel and bore holes under partial vacuum andremoving the gas from the gas bearing rock.

14. The process of extracting methane gas from a coal seam and the gasbearing rock adjacent thereto, which process comprises constructing oneor more tunnels into the coal seam drilling bore holes fromthe tunnelsinto and through the coal seam and into the gas bearing rock, sealingthe tunnel system against the infiltration of atmospheric air,

memes placing the degasification system comprising the tunnel system andbore holes under partial Vacuum and removing the gas from the occludedcoal seam and interstitial gas from the gas bearing rock adjacentthereto.

15. The process of extracting methane gas from gas bearing rook adjacentto a coal seam, which process comprises constructing a tunnel into thecoal seam, drilling bore holes from the tunnel through the coal seaminto the adjacent rock plaoingexplosive charges in the bore holesexploding the charges to fracture the rock, sealing the degasificationsystem comprising the tunnel and bore holes against the infiltration ofatmospheric air, and: removing the gas from the gas bearing roc Intestimony whereof, I have signed this specification.

LEO RANNEY.

